1. Field of the Invention
The present invention relates to a wireless communication system. More particularly, the present invention relates to a method by which a User Equipment (UE) controls a cell reselection priority in a Closed Subscriber Group (CSG) cell and an apparatus thereof.
2. Description of the Related Art
Generally, a mobile communication system has been developed with a goal of providing communication to a mobile user. The mobile communication system has evolved so as to provide a high-speed data communication service as well as a voice communication service.
Recently, Long Term Evolution (LTE), which is a next generation mobile communication system, has been standardized by the 3rd Generation Partnership Project (3GPP). LTE is a technology of realizing high-speed packet-based communication having a transmission rate of about a maximum of 100 Mbps. Various schemes for LTE are under discussion. For example, a scheme of reducing nodes located on communication paths by simplifying a network structure, a scheme of allowing a wireless protocol to be close to a wireless channel, etc.
Meanwhile, unlike a voice communication service, in a data communication service, resources and the like which are assigned according to the quantity of data and a channel state are determined. Thus, in a wireless communication system such as a mobile communication system, management of the assignment of transmission resources in consideration of the quantity of resources available for transmission, a channel state, the quantity of data and the like is performed by a scheduler. A similar function is performed in next generation LTE mobile communication systems. Also, a scheduler located at a base station manages and assigns wireless transmission resources.
Recently, an evolved LTE communication system, i.e., LTE-Advanced (LTE-A), which increases a transmission rate by applying several new technologies to an LTE communication system has been discussed. Research for Closed Subscriber Group (CSG) cell technology in the evolved LTE-A system has also been conducted. The CSG cell is a cell to which only a specific user is allowed to access. An example of a CSG cell is explained below with reference to FIG. 1.
FIG. 1 is a view illustrating a concept of a CSG cell according to the related art.
Referring to FIG. 1, there are two User Equipment (UEs) 110 and 115 in a service area 105 of a CSG cell. UE 110, as a member of the CSG cell, is connected to the CSG cell to perform communication. However, UE 115, as non-member of the CSG cell, is not connected to the CSG cell. Rather, the UE 115 is connected to evolved Node B (eNB) 100, which is a remote macro-cell base station, to perform communication. Each of UE 110 and 115 has a white-list describing whether the UE is a member of a specific CSG cell.